JP3280806B2 - Fluidic flow meter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluidic flow meter for measuring the flow rate of a fluid by measuring the frequency of pressure oscillation of a flow diverted right and left by a target disposed in the flow of the fluid. Things.

[0002]

2. Description of the Related Art Conventionally, for measuring the flow rate of city gas, a mechanical membrane gas meter has been widely used. However, the membrane gas meter has a large image, an old design image, and a high cost. Therefore, a fluid meter is being developed as a gas meter to replace the membrane gas meter. Here, the principle of the conventional fluidic flow meter will be described. First, the configuration of the fluidic flow meter will be described. As shown in FIG.
01 in the flow of the fluid F flowing from
2 are arranged. A right sidewall 107 and a left sidewall 108 are disposed on the left and right of the target 102.

In a fluidic type flow meter, it is known that the fluid F flows alternately to the right and left of the target 102 as shown in FIGS. Divided fluids F1 and F
The return guide 103 is arranged at a position where the two flows collide. The right differential pressure detecting sensor 1 is located at a position where the fluid F1 diverted to the right collides with the return guide 103.
04 is attached, and the left differential pressure detection sensor 1 is located at a position where the fluid F2 diverted to the left collides with the return guide 103.
05 is attached. In the fluidic type flow meter, the fluid F alternately flows to the left and right, so that a periodic minute pressure change occurs in the differential pressure detection sensors 104 and 105. The frequency of the minute pressure change is proportional to the gas flow rate as shown in FIG. The fluidic flow meter measures the flow rate by detecting the frequency of the minute pressure change.

As shown in FIG. 10, the shape of the measuring nozzle of the fluidic flow meter has a rectangular cross section, and an optimum value is experimentally determined as the aspect ratio.
As the gas meter, for example, a full-flow measurement nozzle having a width Wc = 3.8 mm and a height Hc = 38 mm is used. On the other hand, the measurement range of the fluidic flow meter is 3 to 6000 liters / hour with a No. 6 gas meter, and the flow rate that can be measured is limited, so that a large flow rate cannot be measured with a gas meter or the like. Therefore, the present applicants have proposed in JP-A-6-74798 to provide a bypass passage. That is, a plurality of types of fluidic flowmeters having different cross-sectional areas of the bypass passage according to the flow rate to be measured have been manufactured, and an appropriate fluidic flowmeter has been selected and used from among them.

[0005]

However, the conventional fluidic type flow meter has the following problems. (1) In the conventional fluidic flow meter, when a pulsation occurs in the fluid, the frequency of the pulsation is n times (n is an integer) the frequency of the pressure vibration generated by the fluidic flow meter. In some cases, or 1 / n times (n is an integer)
In the case of, the vibration generated by the pulsation is superimposed on the pressure vibration originally generated by the fluidic flow meter, so that when the frequency is measured, the frequency spectrum of the pressure vibration to be originally generated becomes the pulsation Therefore, an error occurs in the flow rate measurement of the fluidic flow meter.

For example, when a fluidic type flow meter is used as a gas meter, if a gas engine heat pump for power generation or cooling / heating is provided upstream of the gas meter, the conventional full-flow type fluidic flow meter has the following problems.
Since the frequency of pulsation 6 to 21 Hz generated by the gas engine heat pump is almost the same as the pressure vibration generated by the gas flow rate measured by the fluidic flow meter,
When the gas engine heat pump is driven, there is a problem that an error occurs in the measured value of the fluidic flow meter. FIG. 7 shows the pressure fluctuation resistance. That is, the horizontal axis indicates the frequency, and the vertical axis indicates the allowable error of the flow rate.
The magnitude of the pulsation when generating 5% is shown. Therefore, FIG. 7 shows that the error is smaller with respect to the pulsation as the graph goes upward. Then, in the full-flow type fluid flow meter, as shown in D, when the pulsation frequency generated by the gas engine heat pump is 6 to 21 Hz, the allowable pressure fluctuation is only about 5 mmH ₂ O.

(2) The problem described in the above (1) is not disclosed at all in JP-A-6-74798, nor is it suggested. However, even when a partition plate is provided and a bypass passage is provided, the problem (1) similarly occurs.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and has as its object to provide a fluidic flow meter which has little influence on measurement even when pulsation occurs in a fluid.

[0009]

Means for Solving the Problems To solve the above problems, (1) The fluidic type flow meter of the present invention is arranged downstream of a measurement nozzle, divides a fluid to the left and right, and applies pressure to the fluid. A target for generating vibration, a piezoelectric element for measuring the pressure of the fluid diverted by the target, and a flow velocity calculating means for calculating the flow velocity from the frequency of the pressure vibration of the fluid measured by the piezoelectric element, and pulsation is generated A fluidic flow meter for measuring the flow rate of a fluid, comprising a partition plate that is located upstream of a measurement nozzle and divides the fluid into a flow rate measurement unit having a fluidic element formed therein and a bypass passage. The entrance area of the bypass passage and the entrance area of the measurement nozzle so that the pressure oscillation generated by the fluid flowing through the nozzle does not coincide with an integral multiple or a fraction of the frequency of the pulsation. And the ratio has been determined.

In the fluidic flow meter according to the present invention, the pulsation source is a gas engine heat pump, and the pulsation frequency is 6 Hz.
The frequency is not less than 21 Hz or less. Further, the fluidic flow meter of the present invention, in the above,
The height of the measuring nozzle is 2 of the height of the bypass passage.
The width of the bypass passage is twice or more the width of the measurement nozzle. Further, in the fluidic flow meter according to the present invention, in the above-mentioned configuration, the measuring nozzle has a width of 3.2 mm and a height of 22 mm,
The bypass nozzle has a width of 11.5 mm or more and a height of 9 m.
m.

[0011]

The partition plate of the fluidic type flow meter according to the present invention having the above-described structure divides the fluid, flows one of the fluids into the flow measuring section, and the other through the bypass passage. A measurement nozzle at the inlet of the flow measurement unit ejects a fluid toward the target. The target causes the fluid ejected from the measurement nozzle to flow alternately to the left and right to generate pressure oscillation in the fluid. The piezoelectric element measures the pressure vibration generated in the fluid by measuring the pressure difference between the pressure on the left and the right of the target. The flow velocity calculating means performs frequency analysis of the pressure vibration of the fluid measured by the piezoelectric element, and calculates the flow velocity from the frequency. on the other hand,
The fluid diverted into the bypass passage by the partition plate enters the bypass passage, and merges with the fluid separated on the measurement nozzle side at the junction.

When a gas engine heat pump is provided upstream of the fluidic flow meter and is operated, the fluid flowing through the fluidic flow meter has a frequency of 6 Hz or more.
A pulsation of a frequency below Hz is generated. However, in the fluidic flow meter of the present invention, the height of the measurement nozzle is at least twice the height of the bypass passage, and the width of the measurement nozzle is at least twice the width of the bypass passage, Further, the measuring nozzle has a width of 3.2 mm and a height of 22 mm.
Wherein the bypass nozzle has a width of 11.5 mm or more;
Since the height is 9 mm, the frequency of the pressure vibration generated by the fluidic flow meter does not match the integral multiple of the frequency of 6 Hz to 21 Hz or a value that is a fraction of the integral multiple.
No errors occur in the fluidic flow meter.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a fluidic flow meter according to an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 shows a side view of the flowmeter main body 19, FIG. 3 shows a bottom view, and FIG. 2 shows a plan view. As shown in FIG.
Is vertically divided by a partition plate 35. Partition plate 3
5, a bypass passage 36 is formed on the upper side (right side in the figure) as shown in FIG. 2, and a flow meter section 37 is formed on the lower side (left side in the figure) as shown in FIG. Have been.
On the left side of the measurement nozzle 11, a flow sensor inlet 38 is formed by being partitioned by a regain network 29.

Next, the configuration of the flow meter section 37 will be described with reference to FIG. FIG. 3 is a bottom view of FIG. 1 as viewed from the left side. On the extension of the flow path of the measurement nozzle 11, the first target 12
Is arranged. The first target 12 has a heart shape, and is arranged such that the concave portion is located on the upstream side. On the left side of the first target 12, a left side wall 18 is arranged, and on the right side, a right side wall 17 is arranged. Also, downstream of the first target 12,
The second target 16 is arranged. A regain net 29 is attached to the lower surface of the measurement nozzle 11. In this embodiment, the regain network 29 has a wire diameter of 0.1.
An 8 mm, 50 mesh wire mesh is used. The regain network 29 is for separating the flow meter section 37 from the flow sensor inlet 38.

In a fluidic flow meter, the fluid F is
It is known that the first target 12 and the second target 16 alternately flow to the left and right. The return guide 13 is disposed at a position where the divided fluid flows F1 and F2 collide with each other. A right differential pressure detection sensor 14 and a left differential pressure detection sensor 15 are attached to both sides of the downstream end of the measurement nozzle 11. In the fluidic flow meter, the fluid F
Flow alternately to the left and right, and by taking the differential pressure between the right differential pressure detection sensor 14 and the left differential pressure detection sensor 15 that are piezoelectric elements, a periodic minute pressure change is measured. It is known that the frequency of the minute pressure change is proportional to the gas flow rate. The fluidic flow meter measures the flow rate by detecting the frequency of the minute pressure change.

Measuring nozzle 11 and bypass passage inlet 2
FIG. 4 shows a cross-sectional shape taken along the line ZZ in FIG. In this embodiment, the measurement nozzle has a width W1 =
3.2 mm, height H1 = 22 mm. As this value, an optimum value of the aspect ratio obtained by an experiment is used.
The bypass passage entrance 20 has W2 = 30 mm and a height H2 = 9 mm. In another embodiment, 18 mm and 11.5 mm are adopted as W2. Next, the bypass passage 36 will be described with reference to FIGS. FIG. 2 is a plan view of FIG. 1 as viewed from the right. Partition plate 3
A pair of side plates 28 forming the bypass passage entrance 20 are formed at both ends of the entrance section 5. The junction 22 is formed at the end of the bypass passage 36.

The flowmeter main body 19 described above is mounted on a flowmeter mounting portion 30 of a meter main body 31, as shown in an exploded perspective view in FIG. FIG. 5 shows a state where the flowmeter main body 19 is mounted on the flowmeter mounting portion 30. Also,
The meter main body 31 is provided with a fluid input port 32 and a fluid output port 33. The fluid to be measured enters the meter main body 31 from the fluid input port 32 and all flows out from the fluid output port 33. The fluid F flowing from the fluid input port 32 flows through the flow regulating chambers 40 and 41 for averaging the flow velocity distribution, and then flows into the flow meter main body 19 attached to the flow meter mounting portion 30.

Next, the operation of the fluidic flow meter having the above-described configuration will be described. The fluid F flowing into the flowmeter main body 19 is divided into a fluid flowing to the bypass passage 36, a fluid flowing to the flowmeter section 37, and a fluid flowing to the flow sensor inlet 38 by the partition plate 35 and the regain network 29. First, the fluid flowing to the flowmeter unit 37 will be described. The measurement nozzle 11 ejects a fluid toward the first target 12 and the second target 16. The first target 12 and the second target 16 alternately flow the fluid ejected from the measurement nozzle 11 to the left side F2 and the right side F1. By observing the fluid pressure at a fixed point,
Fluid pressure oscillation is occurring. By measuring the differential pressure generated on both sides of the outlet of the measurement nozzle 11 by the right differential pressure detection sensor 14 and the left differential pressure detection sensor 15 installed on both sides of the exit of the measurement nozzle 11, the pressure vibration generated in the fluid is measured. Is measured. The microcomputer, which is a flow rate calculating means (not shown), analyzes the frequency of the pressure oscillation of the fluid measured by the right differential pressure detecting sensor 14 and the left differential pressure detecting sensor 15, and calculates the flow velocity from the obtained frequency.

Next, the fluid flowing to the flow sensor inlet 38 will be described. The practical measurement range of the fluidic flow meter is 300 to 6000 liter / h. For this reason, at a small flow rate of 3 to 300 l / h, the flow rate is measured by an IC flow sensor, which is a hot wire flow meter (not shown) attached to the flow sensor inlet 38. It is a hot wire type flow meter that does not measure the flow rate with the IC flow sensor in all areas, so the power consumption is large, and in a gas meter that intends to supply power for 10 years with one lithium battery, This is because it is necessary to switch to a fluidic flow meter that consumes as little power as possible.

On the other hand, the fluid diverted to the bypass passage 36 by the partition plate merges with the fluid separated on the measurement nozzle 11 side at the junction 22. Here, the flow rate divided into the flow meter unit 37 is determined by the shape of the entrance area of the measurement nozzle 11 and the cross-sectional shape of the bypass passage entrance 20. And
The width W2 of the bypass passage entrance 20 is set to W
By setting 2 = 30 mm, 18 mm, and 11.5 mm, the pressure vibration generated by the fluid diverted to the flow meter unit 37 can be made not to coincide with the pulsation frequency of 6 to 21 Hz generated by the gas engine heat pump. Has been confirmed by experiments.

That is, FIG. 7 shows pressure fluctuation resistance.
The horizontal axis indicates the frequency, and the vertical axis indicates the magnitude of the pulsation when the allowable error of the flow rate is ± 2.5%. Therefore, FIG. 7 shows that the error is smaller with respect to the pulsation as the graph goes upward. Then, in the fluidic flow meter of W2 = 30 mm of the present embodiment, as shown in A, when the pulsation frequency generated by the gas engine heat pump is 6 to 21 Hz, the allowable pressure fluctuation is:
The value is more than about twice that of the full flow type. Similarly, in the fluidic flow meter of W2 = 18 mm and 11.5 mm of the present embodiment, as shown in B and C, when the pulsation frequency generated by the gas engine heat pump is 6 to 21 Hz, the allowable pressure fluctuation is , Which is more than twice the value of the full-flow type.

As described in detail above, according to the fluidic type flow meter of the present embodiment, the fluid is supplied to the flow rate measuring section 37 having the fluidic element and the bypass passage upstream of the measuring nozzle 11. Partition plate 3 divided into 36
The pressure oscillation generated by the fluid flowing through the measurement nozzle 11 has a pulsation frequency 6 generated by a gas engine heat pump provided upstream of the fluidic flow meter.
Since the ratio between the entrance area of the bypass passage and the entrance area of the measurement nozzle is determined so as not to be equal to an integral multiple of 1 to 21 Hz or a fraction of an integral number, pulsation occurs in the fluid by the gas engine heat pump. However, the pressure vibration generated in the fluidic flow meter is not affected, and no error occurs in the fluidic flow meter.

In the fluidic type flow meter of this embodiment, the height H1 of the measuring nozzle 11 is 22 mm or more, which is at least twice as large as the height H2 of the bypass passage entrance 20, and the width H2 of the bypass passage entrance 20 is 30 mm. , 18mm, 11.5m
Since m is at least twice as large as the width H1 of the measurement nozzle 11 = 3.2 mm, even if pulsation occurs in the fluid by the gas engine heat pump, the pressure oscillation generated by the fluidic flow meter may be affected. No errors occur in the fluidic flow meter.

The above-described embodiment does not limit the present invention in any way, and various modifications and improvements can be made without departing from the scope of the present invention. For example, in the present embodiment, the gas engine heat pump is described as a source of pulsation. However, even if it is another source, it does not coincide with an integral multiple of the frequency of pulsation generated by the source, or 1 / integer. The same applies if the ratio between the entrance area of the bypass passage entrance 20 and the entrance area of the measurement nozzle 11 is determined. In this embodiment, the No. 6 gas meter has been described as a gas meter. However, when the present invention is applied to a gas meter of another type, the width and height of the bypass passage entrance 20 are changed and used.

[0025]

As is apparent from the above description, according to the fluidic type flow meter of the present invention, the fluid flow measuring section having the fluidic element formed upstream of the measuring nozzle and the bypass passage are provided. And a partition plate for dividing into
A bypass passage is provided so that the pressure oscillation generated by the fluid flowing through the measurement nozzle does not coincide with an integral multiple or a fraction of the frequency of the pulsation generated by the gas engine heat pump provided upstream of the fluidic flow meter. The ratio between the inlet area of the nozzle and the inlet area of the measurement nozzle is determined, so even if pulsation occurs in the fluid due to the gas engine heat pump, the pressure oscillation generated by the fluidic flow meter is not affected. No errors occur in the fluidic flow meter.

[Brief description of the drawings]

FIG. 1 is a side view showing a configuration of a main body of a fluidic flow meter according to an embodiment of the present invention.

FIG. 2 is a plan view of FIG.

FIG. 3 is a bottom view of FIG. 1;

FIG. 4 is a sectional view of a measurement nozzle 11 and a bypass passage entrance 20;

FIG. 5 is an explanatory diagram showing a flow in a fluidic flow meter.

FIG. 6 is an exploded perspective view showing a configuration of a fluidic flow meter.

FIG. 7 is an experimental data diagram showing resistance to pulsation.

FIG. 8 is a first explanatory diagram for explaining the principle of a conventional fluidic flow meter.

FIG. 9 is a second explanatory view for explaining the principle of a conventional fluidic flow meter.

FIG. 10 is a cross-sectional view showing the shape of a measurement nozzle of a conventional full-flow fluidic flow meter.

FIG. 11 is a data diagram showing a relationship between a vibration frequency and a gas flow rate.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Measurement nozzle 12 First target 13 Return guide 14 Right differential pressure detection sensor 15 Left differential pressure detection sensor 16 Second target 17 Right side wall 18 Left side wall 19 Flowmeter main body 20 Bypass passage entrance 28 Side plate 29 Regain net 35 Partition Plate 38 Inlet for flow sensor 39 Junction

Continued on the front page (73) Patent holder 000116633 Aichi Watch Electric Co., Ltd. 1-270, Millennial, Atsuta-ku, Nagoya-shi, Aichi (73) Patent holder 000156813 Kansai Gas Meter Co., Ltd. 10 (73) Patent holder 000142425 Kinmon Manufacturing Co., Ltd. 13-1, Oharacho, Itabashi-ku, Tokyo (73) Patentee 000150109 Takenaka Manufacturing Co., Ltd. 1-15-1 Nakagawa Nishi, Ikuno-ku, Osaka-shi, Osaka (73) Patent holder 000222211 Toyo Gas Meter Co., Ltd. 2795 Motoe, Shinminato-shi, Toyama Prefecture (72) Inventor Yukio Kimura 507-2 Shinhocho, Tokai-shi, Aichi Prefecture Toho Gas Co., Ltd. 507-2 Shinhocho, Tokai-shi Toho Gas Co., Ltd. (72) Inventor Yasushi Mizukoshi 2975 Motoe, Shinminato-shi, Toyama Toyo Gas Meter Co., Ltd. Table 9-10 (72) Inventor Shigenori Okamura Osaka Osaka Gas Co., Ltd. 4-1-2, Hirano-cho, Chuo-ku, Osaka-shi (72) Inventor Koichi Kanda 2-70, Chitose 1-chome, Atsuta-ku, Nagoya-shi, Aichi Pref. Former Masanobu 2-10-16 Higashi-Kobashi, Higashi-Nari-ku, Osaka-shi, Osaka Inside Kansai Gas Meter Co., Ltd. (72) Inventor Naoshi Isshiki 1-2-3 Shimura, Itabashi-ku, Tokyo Kinmon Manufacturing Co., Ltd. Central Research Institute (72) Invention Person Mineyuki Ude 3-15-15 Asahi-cho, Funabashi-shi, Chiba Prefecture (56) References JP-A-4-326020 (JP, A) JP-A-4-326019 (JP, A) (58) Fields investigated (Int .Cl. ⁷ , DB name) G01F 1/20 G01F 1/72

Claims (4)

(57) [Claims] 1. A target which is disposed downstream of a measurement nozzle and divides a fluid to the left and right to generate pressure oscillation in the fluid, a piezoelectric element which measures the pressure of the fluid diverted by the target, and a piezoelectric element which measures the pressure. Flow rate calculating means for calculating the flow rate from the frequency of the pressure oscillation of the fluid, and measuring the flow rate of the fluid in which pulsation occurs. A partition plate that divides the flow rate measurement unit having the Dick element formed therein into a bypass passage, wherein the pressure vibration generated by the fluid flowing through the measurement nozzle is an integral multiple of the frequency of the pulsation, or a fraction of an integer. Wherein the ratio between the entrance area of the bypass passage and the entrance area of the measurement nozzle is determined so as not to coincide with the flow path. 2. The fluid flow meter according to claim 1, wherein the pulsation source is a gas engine heat pump, and the pulsation frequency is 6 Hz or more and 21 Hz or less. 3. The apparatus according to claim 2, wherein the height of the measurement nozzle is two times the height of the bypass passage.
The width of the bypass passage is twice or more as large as the width of the measurement nozzle. 4. The apparatus according to claim 1, wherein the measurement nozzle has a width of 3.2 mm and a height of 22 mm, and the bypass nozzle has a width of 11.5 mm or more and a height of 9 m.
m, a fluidic flow meter.